Process for preparing molybdenum-containing compositions useful for improved fuel economy of internal combustion engines

ABSTRACT

Molybdenum-containing compositions prepared by reacting: 
     (a) a phosphorus-containing acid represented by the formula: ##STR1##  wherein each X and X&#39; is independently oxygen or sulfur, each n is zero or one and each R is independently the same or a different hydrocarbon-based radical; and 
     (b) at least one hexavalent molybdenum oxide compound, and 
     (c) hydrogen sulfide, 
      in the presence of 
     (d) a polar solvent are useful as additives for lubricants. Internal combustion engines, especially gasoline engines, when lubricated by said additive-containing lubricants exhibit improved fuel economy.

Reference to Related Applications.

This application is a continuation of co-pending application U.S. Ser.No. 117,891, filed Feb. 1, 1980, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to sulfur-, phosphorus- and molybdenum-containingcompositions made from phosphorus-containing acids. More specificallythis invention relates to processes for preparing these sulfur-,phosphorus- and molybdenum-containing compositions, which are useful asadditives in lubricants. Additionally, this invention relates toconcentrates of these compositions and to lubricant compositionscomprising these compositions. This invention also relates to methodsfor reducing fuel consumption by lubricating an internal combustionengine with these lubricating compositions.

2. Description of the Prior Art

Sulfur-containing molybdenum salts of phosphorus-containing acids andprocesses for preparing said compositions have been described in U.S.Pat. Nos. 3,223,625; 3,256,184; 3,400,140; 3,494,866; 3,840,463, and4,156,099. These U.S. Patents are hereby incorporated by reference fortheir disclosures in this regard.

A principal object of the present invention is to provide novel sulfur-,phosphorus- and molybdenum-containing compositions made fromphosphorus-containing acids as well as processes for making them.

Another object is to provide novel sulfur-, phosphorus- andmolybdenum-containing compositions made from phosphorus-containing acidswhich exhibit friction reducing properties in lubricants.

Still another object is to provide novel sulfur-, phosphorus- andmolybdenum-containing compositions made from phosphorus-containing acidshaving improved incorporation of molybdenum.

An additional object is to provide novel concentrates comprising thesenovel sulfur-, phosphorus- and molybdenum-containing compositions.

Another additional object is to provide novel lubricant compositions ofthese novel, friction-reducing, sulfur-, phosphorus- andmolybdenum-containing compositions.

A further object is to provide a novel method for reducing fuelconsumption by lubricating an internal combustion engine with thesenovel, friction-reducing, sulfur-, phosphorus- and molybdenum-containingcompositions.

These and other objects of the invention are accomplished by providing aprocess for preparing a composition which comprises reacting:

(a) A phosphorus-containing acid represented by the formula: ##STR2##wherein each X and X' is independently oxygen or sulfur, each n is zeroor one, and each R is independently the same or a differenthydrocarbon-based radical;

(b) at least one hexavalent molybdenum oxide compound, and

(c) hydrogen sulfide,

in the presence of

(d) a polar solvent.

Typical phosphorus-containing acids (a) from which the compositions ofthis invention can be made are known. Illustrative examples of somepreferred phosphorus- and sulfur-containing acids are:

1. Dihydrocarbylphosphinodithioic acids, such as amylphosphinodithioicacid, corresponding to the formula, ##STR3## 2. S-hydrocarbyl hydrogenhydrocarbylphosphonotrithioates, such as S-amyl hydrogenamylphosphonotrithioate, corresponding to the formula, ##STR4## 3.O-hydrocarbyl hydrogen hydrocarbylphosphonodithioates, such as O-amylhydrogen amylphosphonodithioate, corresponding to the formula, ##STR5##4. S,S-dihydrocarbyl hydrogen phosphorotetrathioates, such as diamylhydrogen phosphorotetrathioate, corresponding to the formula, ##STR6##5. O,S-dihydrocarbyl hydrogen phosphorotrithioates, such as O,S-diamylhydrogen phosphorotrithioate, corresponding to the formula, ##STR7## 6.O,O-dihydrocarbyl hydrogen phosphorodithioates, such as O,O-diamylhydrogen phosphorodithioate, corresponding to the formula, ##STR8##

Preferred acids of the formula ##STR9## are readily obtainable from thereaction of phosphorus pentasulfide (P₂ S₅) and an alcohol or a phenol.The reaction involves mixing at a temperature of about 20° to about 200°C., 4 moles of the alcohol or a phenol with one mole of phosphoruspentasulfide. Hydrogen sulfide is liberated in this reaction. Theoxygen-containing analogs of these acids are conveniently prepared bytreating the preferred dithioic acid with water or steam which, ineffect, replaces one or both of the sulfur atoms.

Thus, as previously mentioned, the preferred phosphorus-containing acidsare phosphorus- and sulfur-containing acids. These preferred acids morepreferably include those wherein at least one X is sulfur, morepreferably both of X are sulfur; at least one X' is oxygen or sulfur,more preferably both of X' are oxygen and n is 1. Mixtures of acids maybe employed according to this invention.

The terminology of "hydrocarbon-based radical" as used herein, ("herein"includes the appended claims) is used to define a substantiallysaturated monovalent radical derived from a hydrocarbon by removal of ahydrogen from a carbon atom of the hydrocarbon. This carbon atom isdirectly connected to the remainder of the molecule. Thesehydrocarbon-based radicals are derived from aliphatic hydrocarbons,cyclo-aliphatic hydrocarbons, aromatic hydrocarbons, mixedaliphatic-cyclo-aliphatic hydrocarbons, mixed aliphatic aromatichydrocarbons, and mixed cyclo-aliphatic-aromatic hydrocarbons.Therefore, these hydrocarbon-based radicals would be referred to asaliphatic-based radicals, cyclo-aliphatic-based radicals, etc. The basehydrocarbons from which these radicals are derived may contain certainnon-reactive or substantially non-reactive polar or non-hydrocarbonsubstituents.

The terminology "substantially saturated" as used herein is intended todefine radicals free from acetylenic unsaturation (--C.tbd.C--) in whichthere is not more than one ethylenic linkage (--C═C--) for every 10carbon-to-carbon (preferably 20) covalent bonds. The so-called "doublebonds" in the aromatic ring (e.g., benzene) are not to be considered ascontributing to unsaturation with respect to the terminology"substantially saturated". Usually there will be no more than an averageof one ethylenic linkage per substantially saturated monovalent radicalas described herein. Preferably, (with the exception of aromatic rings)all the carbon-to-carbon bonds in a substantially saturated radical willbe saturated linkages; that is, the radical will be free from acetylenicand ethylenic linkages.

In general, the hydrocarbon-based radical may contain up to about 30carbon atoms with a preferred range of carbon atoms being from one toabout 20. The hydrocarbon-based radicals may contain certainnon-reactive or substantially non-reactive polar or non-hydrocarbonsubstituents which do not materially interfere with the reactions orcompositions herein, as will be recognized by those skilled in the art.Representative non-hydrocarbon or polar substituents include halosubstituents, such as chloro, fluoro, bromo and iodo; nitro; loweralkoxy, such as butoxy and hexyloxy; lower alkyl thio, such aspentylthio and heptylthio; hydroxy; mercapto; ##STR10## and the like. Asa general rule, and particularly when the compositions of this inventionare to be used as lubricant additives, the degree of substitution andnature of the substituent of the hydrocarbon-based radical is such thatthe predominantly hydrocarbon character of the radical is not destroyed.Thus, in view of this requirement, these radicals normally have no morethan four substituents per radical, and usually, not more than onesubstituent for every 10 carbon atoms in the radical. Preferably, thehydrocarbon-based radical is a purely hydrocarbyl (i.e., a hydrocarbonradical containing only carbon and hydrogen atoms).

The term "lower" when used herein to denote radicals such as lower alkylis intended to describe a radical containing up to seven carbon atoms.

Desirable compositions of this invention include those made fromphosphorus-containing acids wherein each R is hydrocarbyl, particularly,independently alkyl, aryl, alkaryl and arylalkyl of up to about 30carbon atoms, more preferably from three to about 20 carbon atoms. Thepreferred R groups are alkyl and alkaryl, preferably alkyl.

The hexavalent molybdenum oxide compounds (b) useful for this inventionare water-soluble hexavalent molybdenum oxide compounds which are acidicunder aqueous conditions. The aqueous chemistry of hexavalent molybdenumoxide compounds is well known to those of ordinarily skill in the artand further discussion is not necessary.

These acidic water-soluble hexavalent molybdenum compounds can beobtained from molybdenum trioxide-containing compounds or mixtures oftwo or more of these compounds.

These molybdenum trioxide-containing compounds include molybdenumtrioxide (MoO₃) and compounds that are made from molybdenum trioxide.The molybdenum trioxide-containing compounds include MoO₃, molybdenumtrioxide hydrates, molybdic acid, ammonium molybdate, alkali metalmolybdates (e.g., sodium or potassium) and heteropolyacid molybdates(e.g., phosphomolybdic acid).

The preferred acidic water-soluble hexavalent molybdenum oxide compoundsare molybdenum trioxide; molybdic acid; the heteropolyacid molybdates,especially the phosphomolybdates; those generated by acidification ofalkali metal molybdates or ammonium molybdates with, e.g., hydrochloricacid, acetic acid or sulfuric acid; and those generated in an aqueoussolution of MoO₃ or its hydrates, wherein the solubility in water of theMoO₃ or its hydrates has been enhanced by the addition of an acid orbase.

Also useful as (b) are the hexavalent molybdenum oxyhalides such asMoOCl₄, MoO₂ Cl₂, MoO₂ Br₂, Mo₂ O₃ Cl₆, MoOF₄ and mixtures thereof whichcan be hydrolyzed by water to the acidic water-soluble hexavalentmolybdenum oxide compounds.

A more detailed discussion of the nature of molybdenumtrioxide-containing compounds, particularly concerning the description,preparation, acidity and water solubility of these compounds, can befound in D. H. Killeffer and A. Linz, Molybdenum Compounds, TheirChemistry and Technology, Interscience Publishers, New York, 1952,Chapters 4, 6, 7 and 8; and F. A. Cotton and G. Wilkinson, AdvancedInorganic Chemistry, A Comprehensive Text, 2nd Edition, IntersciencePublisher-A division of John Wiley and Sons, New York, London, Sidney,1966, pages 930-960, which are hereby incorporated by reference fortheir disclosures in this regard.

Normally the hexavalent molybdenum compound (b) or its precursor isdispersed or dissolved in a polar solvent (d). Alternatively, (a) and(b), or their precursors, may be first combined followed by the additionof (d). In some situations it may be desirable to generate (a) and/or(b) in situ, preferably in the presence of (d). In the case of (a), forexample, a metal salt of the phosphorus-containing acid (e.g., alkalimetal) could be acidified in the presence of (b) to yield (a). In thecase of (b), for example, a molybdenum trioxide-containing compound canbe used to generate an acidic water-soluble hexavalent molybdenumcompound by acidifying an alkali metal molybdate in the presence of (a)and (d) to generate (b) in situ.

For the purpose of this invention it is necessary that a reactionmixture of (a) and (b) is first prepared, preferably in the presence of(d), before reaction with hydrogen sulfide (c).

Hydrogen sulfide (c) is commercially available and can be introducedinto the reaction chamber either above or below the surface of thereaction mixture of (a) and (b) in the presence of (d).

Another source can be H₂ S generated in situ. For example, alkali metalsufides, e.g., Na₂ S, could be acidified with HCl to generate in H₂ S inthe presence of (a), (b) and (d).

The polar solvent (d) useful for this invention includes water, organicpolar solvents such as alcohols, ethers, ketones, and mixtures thereof.The preferred polar solvent (d) is water and mixtures of water and oneor more other organic polar solvents. The preferred organic polarsolvents are the lower alkyl alcohols, ethers and ketones.

In addition to the polar solvents, the reaction may be carried out inthe presence of a substantially inert liquid solvent/diluent medium.This solvent/diluent medium desirably serves to maintain contact of thereactants and facilitate control of the reaction temperatures. Examplesof suitable solvent/diluent media include aliphatic and aromatichydrocarbons as benzene, toluene, naphtha, mineral oil, hexane;chlorinated hydrocarbons as dichlorobenzene and heptylchloride.

As used in the specification and the appended claims, the term"substantially inert" when used to refer to solvents/diluents, and thelike, is intended to mean that the solvent/diluent, etc., issufficiently inert to chemical or physical change under the conditionsin which it is used so as not to materially interfere in an adversemanner with the preparation, storage, blending and/or functioning of thecompositions, additive, compound, etc., of this invention in the contextof its intended use. For example, small amounts of a solvent/diluent,etc. can undergo minimal reaction or degradation without preventing themaking and using of the invention as described herein. In other words,such reaction or degradation, while technically discernible, would notbe sufficient to deter the practical worker of ordinary skill in the artfrom making and using the invention for its intended purposes."Substantially inert" as used herein is, thus, readily understood andappreciated by those of ordinary skill in the art.

As used in the specification and the appended claims, the term"solvent/diluent medium" is intended to include those solvent/media inwhich independently each of the reactants are soluble or stablydispersible. The term "stably dispersible" as used in the specificationand the appended claims is intended to mean a composition (e.g., asingle compound, a mixture of two or more compounds, etc.) is capable ofbeing dispersed in a given medium to an extent which allows it tofunction in its intended manner. Thus, for example, where a compositionis prepared by a reaction in an oil, it is sufficient that the reactantsbe capable of being suspended in the oil in a manner sufficient to allowthe reaction to occur and the formation of the composition. Thus, theterm "solvent/diluent medium" is understood and can be used in aconventional manner by those of ordinary skill in the art.

The product of reacting components (a), (b) and (c) in the presence of(d) may be used as a lubricant additive, however, it is preferred that(d) be removed particularly when (d) is water. The compositions made byreacting (a), (b) and (c) in the presence of (d) sometimes may beaccompanied by the formation of by-products and/or excesssolvent/diluent medium which may lessen its commercial appeal.Accordingly, the polar solvent (d), undesirable by-products and/orexcess or undesired solvent/diluent medium can be separated from thecompositions of this invention by techniques known in the art, e.g.,filtration, evaporation (e.g., stripping), etc., to obtain a moredesirable product. Alternatively, if the solvent/diluent medium is, forexample, a base suitable for use in the lubricating compositions of thisinvention, the product can be left in the solvent/diluent medium andused to form the lubricating compositions as described below.

A reaction mixture of (a) and (b) must first be prepared before reactionwith (c) in the presence of (d). It is preferred that (d) is presentwhen preparing the reaction mixture of (a) and (b); and it isparticularly preferred to disperse or dissolve (b) in (d) before contactwith (a). This reaction mixture may be conveniently prepared within atemperature range of from about 0° up to about 150° C., preferably fromabout 25° C. up to about 100° C.

The reaction of (a), (b) and (c) in the presence of (d) may beconveniently carried out at within the temperature range of about0°-150° C. Although it is not necessary, it is preferred to control thetemperature so that it is reasonably constant throughout the course ofthe reaction, It is particularly preferred to control the temperaturewithin the range of from about 50° C. up to about 100° C.

The period of time for reaction varies with several factors includingnature and amount of reactants, reaction equipment, solvent/diluentmedium, degree of mixing, and the like.

For the purposes of this invention, the molecular weight of aphosphorus-containing acid (a) is equal to its equivalent weight and,therefore, one mole of (a) is equal to its equivalent weight, which isdetermined by substituting its "acid number" in the following equation:##EQU1## The "acid number" is defined as the number of milligrams of KOHused to raise the pH of one gram of sample under aqueous conditions toabout 4.0. The pH of about 4.0 can be determined by the use of anindicator that changes color in the range of 3.0 to 4.5 such asbromphenol blue or by electrical means such as a pH-meter.

For the purposes of this invention, the ratio of reactants (a) to (b) isfrom about 0.5 up to about four moles of the phosphorus-containing acid(a) per mole of molybdenum in (b) (e.g., one mole of Na₂ MoO₄ containsone mole of molybdenum; ammonium paramolybdate, (NH₄)₆ Mo₇ O₂₄.4H₂ O,contains seven moles of molybdenum). A ratio of at least about 0.5 moleof hydrogen sulfide per mole of molybdenum in the reaction mixture of(a) and (b) is desirable.

Therefore, the range ratios of (a):(b):(c) is from about 0.5 up to aboutfour moles of (a):one mole of molybdenum in (b):at least 0.5 mole of H₂S. A ratio of about 1:1:1.5 is optimum, although an excess (i.e.,1:1:>1.5) of hydrogen sulfide can be used to insure complete reaction. Aratio of 1:1:4 or more may be used, but a ratio of 1:1:2 should besufficient to insure complete reaction. Excess hydrogen sulfide can beremoved by blowing the reaction mixture with an inert gas such asnitrogen.

The polar solvent (d) is essentially a promotor or contact agent.Therefore, minimum amount of polar solvent (d) is that amount necessaryfor the reaction of (a), (b) and (c) to proceed (i.e., the point atwhich the hydrogen sulfide will react with (a) and (b) in the presenceof (d)). Generally, enough (d) is used to disperse or, preferably,dissolve the molybdenum trioxide containing compounds or themolybdenum-oxyhalide compounds previously described. Usually from aboutone up to about four parts of (d) will be used for each part by weightof the above-described molybdenum compound used. Substantial amounts of(d) in excess of this would not be uncommon, but would not beadvantageous.

This invention is exemplified in the following examples. Of course,these examples are not intended as limiting this invention asmodification of the examples by ordinary expedients will be readilyapparent to those of ordinary skill in the art.

In all examples, unless otherwise stated, all temperatures are in °C.;all parts are parts by weight and all percentages are derived from partsby weight.

EXAMPLE 1

A reaction mixture is prepared by the addition of 2035 parts (9.17moles) of P₂ S₅ to 7335 parts (36.68 moles) of a commercially availableC₁₂ -₁₄ alcohol at 80° C. under a nitrogen blanket. The P₂ S₅ is addedover a two-hour period and the exotherm increases the temperature to 95°C. during the addition period. The hydrogen sulfide formed as a resultof the reaction is removed continuously and trapped by caustic sodasolution. The reaction mixture is allowed to cool while stirring for twohours under nitrogen. The reaction mixture is filtered to yield thedesired O,O-di-C₁₂ -₁₄ phosphorodithioic acid which has an acid numberof 96.

EXAMPLE 2

The procedure for Example 1 is repeated except the C₁₂ -₁₄ alcohol isreplaced on an equimolar basis with 2-ethylhexyl alcohol to yield thedesired O,O-di-2-ethylhexyl phosphorodithioic acid which has an acidnumber of 137.

EXAMPLE 3

A reaction mixture is prepared by adding a mixture of 584 parts (1 mole)of the O,O-di-C₁₂ -₁₄ phosphorodithioic acid prepared in Example 1 and500 parts of toluene to a room temperature (26° C.) solution of 40 parts(1 mole) of sodium hydroxide, 190 parts of water and 144 parts (1 mole)of molybdenum trioxide prepared by heating until a clear solution isobtained. After the addition is complete, 100 parts (1 equivalent) ofconcentrated hydrochloric acid is added to the reaction mixture. Thereaction mixture is heated at 40° C. for two hours.

Hydrogen sulfide (90 parts; 2.6 moles) is added to the reaction mixtureby subsurface addition over a period of three hours. During the hydrogensulfide addition, the temperature of the reaction mixture is increasedto 90° C.

The reaction mixture is then purged of excess hydrogen sulfide byblowing with nitrogen, stripped under vacuum at 94° C. and filtered toyield the desired sulfur-, phosphorus- and molybdenum-containingcomposition made from an O,O-di-C₁₂ -₁₄ phosphorodithioic acid.

EXAMPLE 4

A reaction mixture is prepared by the addition of 3,275 parts (8 moles)of the O,O-di-2-ethylhexylphosphorodithioic acid prepared in Example 2to a room temperature slurry of 1,152 parts (8.0 moles) of molybdenumtrioxide in 2,000 parts of water. The reaction mixture is heated to 80°C. and 533 parts hydrogen sulfide is added by subsurface addition over a6.5-hour period. The reaction mixture is maintained at 80°-90° C. duringthe hydrogen sulfide addition. The reaction mixture is then purged ofexcess hydrogen sulfide by blowing with nitrogen and stripped at95°-100° C. under vacuum to yield the residue as the desired sulfur-,phosphorus- and molybdenum-containing composition made from anO,O-di-2-ethylhexylphosphorodithioic acid.

EXAMPLE 5

An aqueous solution of phosphomolybdic acid is prepared by heating 360parts (2.5 moles) of molybdenum trioxide, 24 parts of 85% phosphoricacid and 2,000 parts of water at boiling for three hours, then filteringthrough filter paper and washing the residue with 150 parts of water.The total volume of the resulting solution is reduced to yield 921 partsof solution containing 19.37% molybdenum.

EXAMPLE 6

A reaction mixture is prepared by the dropwise addition of 1,475 parts(3.0 moles) of the phosphomolybdic acid prepared in Example 5 to 1,228parts (3 moles) of the O,O-di-2-ethylhexylphosphorodithioic acidprepared in Example 2 at room temperature over a one-hour period. Thereaction mixture is then held at 55° C. for 3.5 hours. The reactionmixture is heated to reflux while blowing with hydrogen sulfide beneaththe surface. The reaction mixture is held at 90°-95° C. for three hoursduring which hydrogen sulfide blowing is continued. A total of 242 partsof hydrogen sulfide is added to the reaction mixture. The reactionmixture is then purged of excess hydrogen sulfide by blowing withnitrogen. Toluene (1000 parts) is added to the reaction mixture andwater is removed by azeotropic distillation. The reaction mixture isfiltered and then stripped of toluene at 95° C. under vacuum to yieldthe desired sulfur-, phosphorus- and molybdenum-containing compositionmade from an O,O-di-2-ethylhexylphosphorodithioic acid.

EXAMPLE 7

A reaction mixture is prepared by adding a mixture of 2050 parts (5.0moles) of the O,O-di-2-ethylhexylphosphorodithioic acid prepared inExample 2 and 2,500 parts of toluene to a room temperature solutionprepared by heating parts (5 moles) of sodium hydroxide, 1,000 parts ofwater and 720 parts (5.0 moles) of molybdenum trioxide until a clearsolution is obtained and then adding 39 parts (0.25 mole) of 85%phosphoric acid to the solution. After addition is complete, 500 parts(5 moles) of concentrated hydrochloric acid is added to the reactionmixture and then heated at 40° C. for two hours. Hydrogen sulfide (318parts; 9.35 moles) is added to the reaction mixture by subsurfaceaddition over a period of ten hours. During the hydrogen sulfideaddition, the temperature of the reaction mixture is increased toreflux. The reaction mixture is then purged of excess hydrogen sulfideby blowing with nitrogen and stripped under vacuum at 90° C. Toluene(2,000 parts) is added to the reaction mixture which is filtered andthen stripped to yield the desired sulfur-, phosphorus- andmolybdenum-containing composition made fromO,O-di-2-ethylhexylphosphorodithioic acid.

EXAMPLE 8

A reaction mixture of 1,152 parts (8 moles) of molybdenum trioxide, 77parts (0.67 mole) of 85% phosphoric acid, 3,000 parts of water and 3,275parts (8 moles) of O,O-di-2-ethylhexylphosphorodithioic acid prepared inExample 2 is heated to 85° C. To the reaction mixture 533 parts ofhydrogen sulfide is added by subsurface addition over a 6.5-hour period.The reaction mixture is maintained at 80°-90° C. during the hydrogensulfide addition. The reaction mixture is then purged of excess hydrogensulfide by blowing with nitrogen and stripped at 95°-100° C. undervacuum to yield the residue as the desired sulfur-, phosphorus- andmolybdenum-containing composition made from anO,O-di-2-ethylhexylphosphorodithioic acid.

As previously indicated, the compositions of this invention are alsouseful as additives for lubricants, in which they function primarily asoxidation inhibitors, antiwear and/or extreme pressure agents andfriction modifiers. They can be employed in a variety of lubricantsbased on diverse oils of lubricating viscosity, including natural andsynthetic lubricating oils and mixtures thereof. These lubricantsinclude crankcase lubricating oils for spark-ignited andcompression-ignited internal combustion engines, including automobileand truck engines, two-cycle engines, aviation piston engines, marineand railroad diesel engines, and the like. They can also be used in gasengines, stationary power engines and turbines and the like. Automatictransmission fluids, transaxle lubricants, gear lubricants,metal-working lubricants, hydraulic fluids and other lubricating oil andgrease compositions can also benefit from the incorporation therein ofthe compositions of the present invention.

Natural oils include animal oils and vegetable oils (e.g., castor oil,lard oil) as well as liquid petroleum oils and solvent-treated oracid-treated mineral lubricating oils of the paraffinic, naphthenic ormixed paraffinic-naphthenic types. Oils of lubricating viscosity derivedfrom coal or shale are also useful base oils. Synthetic lubricating oilsinclude hydrocarbon oils and halo-substituted hydrocarbon oils such aspolymerized and interpolymerized olefins [e.g., polybutylenes,polypropylenes, propylene-isobutylene copolymers, chlorinatedpolybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes), etc.and mixtures thereof]; alkylbenzenes (e.g., dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes, etc.);polyphenols (e.g., biphenyls, terphenyls, alkylated polyphenols, etc.),alkylated diphenyl ethers and alkylated diphenyl sulfides and thederivatives, analogs and homologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc. constitute another class of known syntheticlubricating oils. These are exemplified by the oils prepared throughpolymerization of ethylene oxide or propylene oxide, the alkyl and arylethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropyleneglycol ether having an average molecular weight of 1000, diphenyl etherof polyethylene glycol having a molecular weight of 500-1000, diethylether of polypropylene glycol having a molecular weight of 1000-1500,etc.) or mono- and polycarboxylic esters thereof, for example, theacetic acid esters, mixed C₃ -C₈ fatty acid esters, or the C₁₃ Oxo aciddiester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises theesters of dicarboxylic acids (e.g., phthalic acid, succinic aid, alkylsuccinic acids and alkenyl succinic acids, maleic acid, azelaic acid,suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.)with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycolmonoether, propylene glycol, etc.). Specific examples of these estersinclude dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate,dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctylphthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyldiester of linoleic acid dimer, the complex ester formed by reacting onemole of sebacic acid with two moles of tetraethylene glycol and twomoles of 2-ethylhexanoic acid, and the like.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol ethers such neopentylglycol, trimethylolpropane, pentaerythritol, dipentaerythritol,tripentaerythritol, etc.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-, orpolyaryloxy-siloxane oils and silicate oils comprise another usefulclass of synthetic lubricants (e.g., tetraethyl silicate, tetraisopropylsilicate, tetra-(2-ethylhexyl)silicate,tetra-(4-methyl-2-ethylhexyl)silicate,tetra-(p-tert-butylphenyl)silicate,hexa-(4-methyl-2-pentoxy)-disiloxane, poly(methyl)-siloxanes,poly(methylphenyl)siloxanes, etc.). Other synthetic lubricating oilsinclude liquid esters of phosphorus-containing acids (e.g., tricresylphosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid,etc.), polymeric tetrahydrofurans and the like.

Unrefined, refined and rerefined oils (and mixtures of each with eachother) of the type disclosed hereinabove can be used in the lubricantcompositions of the present invention. Unrefined oils are those obtaineddirectly from a natural or synthetic source without further purificationtreatment. For example, a shale oil obtained directly from retortingoperations, a petroleum oil obtained directly from distillation or esteroil obtained directly from an esterification process and used withoutfurther treatment would be an unrefined oil. Refined oils are similar tothe unrefined oils except they have been further treated in one or morepurification steps to improve one or more properties. Many suchpurification techniques are known to those of skill in the art such assolvent extraction, acid or base extraction, filtration, percolation,etc. Rerefined oils are obtained by processes similar to those used toobtain refined oils applied to refined oils which have been already usedin service. Such rerefined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniquesdirected to removal of spent additives and oil breakdown products.

Generally, the lubricants of the present invention contain an amount ofthe composition of this invention sufficient to provide it with improvedoxidation stability and/or antiwear and/or extreme pressure and/orfriction reducing properties. Normally this amount will be about 0.05%to about 20%. Preferably about 0.1% to about 10%, more preferably up toabout 5% and typically about 0.5% to about 2% of the total weight of thelubricant. In lubricating oils operated under extremely adverseconditions, such as lubricating oils for marine diesel engines, thereaction products of this invention may be present in amounts of up toabout 30% by weight.

The invention also contemplates the use of other additives incombination with the compositions of this invention. Such additivesinclude, for example, auxiliary detergents and dispersants of theash-producing or ashless type, corrosion- and oxidation-inhibitingagents, pour point depressing agents, extreme pressure agents, colorstabilizers and anti-foam agents.

The ash-producing detergents are exemplified by oil-soluble neutral andbasic salts of alkali or alkaline earth metals with sulfonic acids,carboxylic acids, or organic phosphorus acids characterized by at leastone direct carbon-to-phosphorus linkage such as those prepared by thetreatment of an olefin polymer (e.g., polyisobutene having a molecularweight of 1000) with a phosphorizing agent such as phosphorustrichloride, phosphorus heptasulfide, phosphorus pentasulfide,phosphorus trichloride and sulfur, white phosphorus and a sulfur halide,or phosphorothioic chloride. The most commonly used salts of such acidsare those of sodium, potassium, lithium, calcium, magnesium, strontiumand barium.

The term "basic salt" is used to designate metal salts wherein the metalis present in stoichiometrically larger amounts than the organic acidradical. The commonly employed emthods for preparing the basic saltsinvolve heating a mineral oil solution of an acid with a stoichiometricexcess of a metal neutralizing agent such as the metal oxide, hydroxide,carbonate, bicarbonate, or sulfide at a temperature above 50° C. andfiltering the resulting mass. The use of a "promoter" in theneutralization step to aid the incorporation of a large excess of metallikewise is known. Examples of compounds useful as the promoter includephenolic substances such as phenol, naphthol, alkylphenol, thiophenol,sulfurized alkylphenol, and condensation products of formaldehyde with aphenolic substance; alcohols such as methanol, 2-propanol, octylalcohol, cellosolve, carbitol, ethylene glycol, stearyl alcohol, andcyclohexyl alcohol; and amines such as aniline, phenylenediamine,phenothiazine, phenyl-β-naphthylamine, and dodecylamine. A particularlyeffective method for preparing the basic salts comprises mixing an acidwith an excess of a basic alkaline earth metal neutralizing agent and atleast one alcohol promoter, and carbonating the mixture at an elevatedtemperature such as 60°-200° C.

Auxiliary ashless detergents and dispersants are so called despite thefact that, depending on its constitution, the dispersant may uponcombustion yield a non-volatile material such as boric oxide orphosphorus pentoxide; however, it does not ordinarily contain metal andtherefore does not yield a metal-containing ash on combustion. Manytypes are known in the art, and any of them are suitable for use in thelubricants of this invention. The following are illustrative:

(1) Reaction products of carboxylic acids (or derivatives thereof)containing at least about 34 and preferably at least about 54 carbonatoms with nitrogen-containing compounds such as amine, organic hydroxycompounds such as phenols and alcohols, and/or basic inorganicmaterials. Examples of these "carboxylic dispersants" are described inBritish Pat. No. 1,306,529 and in many U.S. patents including thefollowing:

    ______________________________________                                        3,163,603      3,351,552                                                                              3,541,012                                             3,184,474      3,381,022                                                                              3,542,678                                             3,215,707      3,399,141                                                                              3,542,680                                             3,219,666      3,415,750                                                                              3,567,637                                             3,271,310      3,433,744                                                                              3,574,101                                             3,272,746      3,444,170                                                                              3,576,743                                             3,281,357      3,448,048                                                                              3,630,904                                             3,306,908      3,448,049                                                                              3,632,510                                             3,311,558      3,451,933                                                                              3,632,511                                             3,316,177      3,454,607                                                                              3,697,428                                             3,340,281      3,467,668                                                                              3,725,441                                             3,341,542      3,501,405                                                                              Re 26,433                                             3,346,493      3,522,179                                                      ______________________________________                                    

(2) Reaction products of relatively high molecular weight aliphatic oralicyclic halides with amines, preferably polyalkylene polyamines. Thesemay be characterized as "amine dispersants" and examples thereof aredescribed for example, in the following U.S. patents:

    ______________________________________                                               3,275,554                                                                            3,454,555                                                              3,438,757                                                                            3,565,804                                                       ______________________________________                                    

(3) Reaction products of alkyl phenols in which the alkyl group containsat least about 30 carbon atoms with aldehydes (especially formaldehyde)and amines (especially polyalkylene polyamines), which may becharacterized as "Mannich dispersants". The materials described in thefollowing U.S. patents are illustrative:

    ______________________________________                                               3,413,347                                                                            3,725,480                                                              3,697,574                                                                            3,726,882                                                              3,725,277                                                              ______________________________________                                    

(4) Products obtained by post-treating the carboxylic, amine or Mannichdispersants with such reagents as urea, thiourea, carbon disulfide,aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinicanhydrides, nitriles, epoxides, boron compounds, phosphorus compounds orthe like. Exemplary materials of this kind are described in thefollowing U.S. patents:

    ______________________________________                                        3,036,003                                                                              3,282,955    3,493,520                                                                              3,639,242                                      3,087,936                                                                              3,312,619    3,502,677                                                                              3,649,229                                      3,200,107                                                                              3,366,569    3,513,093                                                                              3,649,659                                      3,216,936                                                                              3,367,943    3,533,945                                                                              3,658,836                                      3,254,025                                                                              3,373,111    3,539,633                                                                              3,697,574                                      3,256,185                                                                              3,403,102    3,573,010                                                                              3,702,757                                      3,278,550                                                                              3,442,808    3,579,450                                                                              3,703,536                                      3,280,234                                                                              3,455,831    3,591,598                                                                              3,704,308                                      3,281,428                                                                              3,455,832    3,600,372                                                                              3,708,522                                      ______________________________________                                    

(5) Interpolymers of oil-solubilizing monomers such as decylmethacrylate, vinyl decyl ether and high molecular weight olefins withmonomers containing polar substituents, e.g., aminoalkyl acrylates oracrylamides and poly-(oxyethylene)-substituted acrylates. These may becharacterized as "polymeric dispersants" and examples thereof aredisclosed in the following U.S. patents:

    ______________________________________                                               3,329,658                                                                            3,666,730                                                              3,449,250                                                                            3,687,849                                                              3,519,565                                                                            3,702,300                                                       ______________________________________                                    

The above-noted patents are incorporated by reference herein for theirdisclosures of ashless dispersants.

Extreme pressure agents and corrosion- and oxidation-inhibiting agentsare exemplified by chlorinated aliphatic hydrocarbons such aschlorinated wax; organic sulfides and polysulfides such as benzyldisulfide, bis(chlorobenzyl)disulfide, dibutyl tetrasulfide, sulfurizedmethyl ester of oleic acid, sulfurized alkylphenol, sulfurizeddipentene, and sulfurized terpene; phosphosulfurized hydrocarbons suchas the reaction product of a phosphorus sulfide with turpentine ormethyl oleate; phosphorus esters including principally dihydrocarbon andtrihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite,dicyclohexyl phosphite, pentylphenyl phosphite, dipentylphenylphosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthylphosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecularweight 500)-substituted phenyl phosphite, diisobutyl-substituted phenylphosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate,and barium heptylphenyl dithiocarbamate; Group II metalphosphorodithioates such as zinc dicyclohexylphosphorodithioate, zincdioctylphosphorodithioate, barium di(heptylphenyl)phosphorodithioate,cadmium dinonylphosphorodithioate, and the zinc salt of aphosphorodithioic acid produced by the reaction of phosphoruspentasulfide with an equimolar mixture of isopropyl alcohol and n-hexylalcohol.

The compositions of this invention can be added directly to thelubricant. Preferably, however, they are diluted with a substantiallyinert, normally liquid organic diluent such as mineral oil, naphtha,benzene, toluene or xylene, to form an additive concentrate. Theseconcentrates usually contain about 20-90% by weight of the compositionof this invention and may contain, in addition, one or more otheradditives known in the art or described hereinabove.

The lubricating compositions made according to this invention can beexemplified by a lubricating composition prepared by treating a mineraloil of lubricating viscosity with 1% by weight of the product of Example8.

What is claimed is:
 1. A process for preparing a composition whichcomprises reacting:(a) A phosphorus-containing acid represented by theformula: ##STR11## wherein each X and X' is independently oxygen orsulfur, each n is zero or one, and each R is independently the same or adifferent hydrocarbon-based radical; (b) at least one hexavalentmolybdenum oxide compound, and (c) hydrogen sulfide, in the presence of(d) a polar solvent at a temperature of from about 0° C. up to about150° C. wherein the ratio of reactants of (a):(b):(c) is from about 0.5up to about 4 moles of (a): one mole of molybdenum in (b): at least 0.5mole of H₂ S and (d) is present in at least one minimum amount necessaryfor the reaction of (a), (b) and (c) to proceed; with the proviso that areaction mixture of (a) and (b) is first prepared before reaction withhydrogen sulfide (c).
 2. A process according to claim 1 wherein thehydrocarbon-based radical is an aliphatic-based radical and contains upto about 30 carbon atoms.
 3. A process according to claim 2 wherein thealiphatic-based radical is alkyl and contains from 3 to about 30 carbonatoms.
 4. A process according to claim 3 wherin at least one X issulfur; at least one X' is oxygen; and each n is
 1. 5. A processaccording to claim 4 wherein (d) is water, organic polar solvents ormixtures thereof.
 6. A process according to claim 1 wherein thehexavalent molybdenum oxide compound (b) is an acidic water-solublehexavalent molybdenum compound that is obtained from molybdenum-trioxidecompounds or mixtures of one or more of these compounds.
 7. A processaccording to claim 6 wherein the molybdenum-trioxide compounds aremolybdenum trioxide, molybdenum trioxide hydrate, molybdic acid,ammonium molybdates, alkali metal molybdates, or heteropolyacidmolybdates.
 8. A process according to claim 4 wherein the hexavalentmolybdenum oxide compound (b) is an acidic water-soluble hexavalentmolybdenum compound that is obtained from molybdenum-trioxide compoundsor mixtures of one or more of these compounds.
 9. A process according toclaim 8 wherein the molybdenum-trioxide compounds are molybdenumtrioxide, molybdenum trioxide hydrate, molybdic acid, ammoniummolybdates, alkali metal molybdates, or heteropolyacid molybdates.
 10. Aprocess according to claim 5 wherein the hexavalent molybdenum oxidecompound (b) is an acidic water-soluble hexavalent molybdenum compoundthat is obtained from molybdenum-trioxide compounds or mixtures of oneor more of these compounds.
 11. A process according to claim 10 whereinthe molybdenum-trioxide compounds are molybdenum trioxide, molybdenumtrioxide hydrate, molybdic acid, ammonium molybdates, alkali metalmolybdates, or heteropolyacid molybdates.
 12. A process according toclaim 7 wherein the heteropolyacid molybdates are the phosphomolybdates.13. A process according to claim 9 wherein the heteropolyacid molybdatesare the phosphomolybdates.
 14. A process according to claim 11 whereinthe heteropolyacid molybdates are the phosphomolybdates.
 15. A processaccording to claim 1 wherein (d) is water.
 16. A process according toclaim 4 wherein (d) is water.
 17. A process according to claim 5 wherein(d) is water.
 18. A process according to claim 7 wherein (d) is water.19. A process according to claim 9 wherein (d) is water.
 20. A processaccording to claim 11 wherein (d) is water.
 21. A process according toclaim 14 wherein (d) is water.
 22. A composition prepared according tothe process of claim
 1. 23. A composition prepared according to theprocess of claim
 4. 24. A composition prepared according to the processof claim
 5. 25. A composition prepared according to the process of claim9.
 26. A composition prepared according to the process of claim
 15. 27.A composition prepared according to the process of claim
 16. 28. Acomposition prepared according to the process of claim
 17. 29. Acomposition prepared according to the process of claim
 21. 30. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure or friction reducing properties upto about 30% by weight of at least one composition of claim
 22. 31. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 23. 32. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 24. 33. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 25. 34. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 26. 35. Alubricant composition comprising a major amount of an oil lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 27. 36. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 28. 37. Alubricant composition comprising a major amount of an oil of lubricatingviscosity and an amount sufficient to provide improved oxidationstability, antiwear, extreme pressure, or friction reducing propertiesup to about 30% by weight of at least one composition of claim
 29. 38.An additive concentrate comprising about 20-90% of at least onecomposition of claim 22 and a substantially inert, normally liquidorganic diluent.
 39. An additive concentrate comprising about 20-90% ofat least one composition of claim 23 and a substantially inert, normallyliquid organic diluent.
 40. An additive concentrate comprising about20-90% of at least one composition of claim 24 and a substantiallyinert, normally liquid organic diluent.
 41. An additive concentratecomprising about 20-90% of at least one composition of claim 25 and asubstantially inert, normally liquid organic diluent.
 42. An additiveconcentrate comprising about 20-90% of at least one composition of claim26 and a substantially inert, normally liquid organic diluent.
 43. Anadditive concentrate comprising about 20-90% of at least one compositionof claim 27 and a substantially inert, normally liquid organic diluent.44. An additive concentrate comprising about 20-90% of at least onecomposition of claim 28 and a substantially inert, normally liquidorganic diluent.
 45. An additive concentrate comprising about 20-90% ofat least one composition of claim 29 and a substantially inert, normallyliquid organic diluent.
 46. A method for reducing the fuel consumptionof an internal combustion engine which comprises lubricating said engineduring operation with the lubricant composition of claim
 30. 47. Amethod for reducing the fuel consumption of an internal combustionengine which comprises lubricating said engine during operation with thelubricant composition of claim
 31. 48. A method for reducing the fuelconsumption of an internal combustion engine which comprises lubricatingsaid engine during operation with the lubricant composition of claim 32.49. A method for reducing the fuel consumption of an internal combustionengine which comprises lubricating said engine during operation with thelubricant composition of claim
 33. 50. A method for reducing the fuelconsumption of an internal combustion engine which comprises lubricatingsaid engine during operation with the lubricant composition of claim 34.51. A method for reducing the fuel consumption of an internal combustionengine which comprises lubricating said engine during operation with thelubricant composition of claim
 35. 52. A method for reducing the fuelconsumption of an internal combustion engine which comprises lubricatingsaid engine during operation with the lubricant composition of claim 36.53. A method for reducing the fuel consumption of an internal combustionengine which comprises lubricating said engine during operation with thelubricant composition of claim 37.